Hey Guys-

I've had a mysterious slow brake fluid leak for a few weeks. Every 10 days or so the brake light comes on and I top off. Cannot find the source. Suddenly, tons of white smoke come out of exhaust with a little rougher riding.

Taken to mechanic - first diagnosis : Gaskets - but no loss of coolant or wierd pressure from radiator.

Next day mechanic lets it run, it smokes again. He pull the vaccum line to the engine from the brake booster and smoke stops!

Mechanic says: Master cyclander and booster are leaking and the vaccum is sucking brake fluid into engine and it is burning. Both need to be replaced.

Is this even possible? My rover is broken down out of town. So - I'm dealing with this remotely. Thanks!

Disco Mike and Spike were on a similiar thread a few years back but I dont see the conclusion.

 

Replace master cylinder. Booster is probably fine.

 

he seems to think that if fluid got into booster it would impact the seals within.

 

this would be my inclination as well, and if youve got the money id replace both while in there.

 

I have not seen the fluid ever ruin the seals/diaphragm in the booster. I have seen boosters filled with fluid before, but the diaphragm was still in great shape. Every one I've seen appeared to be made from rubber.

 

If you have fluid in the booster, it is shot, the brake fluid eats up the diaphram. Better start looking foe a new booster/master cylinder.
I would suggest you call Paul Grant, his number is in my signature section, he should have a good guaranteed used one.

 

I disagree. It could take years in that condition to 'eat' the diaphragm. It actually doesn't eat the diaphragm, it softens the material over a (very)long time. If he just found the problem, then replacing the MC would fix it and the Booster would be fine for many more years of service. But it ultimately is up to the owner as to what he wants to do and how much money he has.

 

Yeah. Service manuals just say that to CYA. I worked in an import garage as a teenager and saw many many Hondas with bad master cylinders and probably half were leaking into the booster. The Honda manual says that brake fluid will damage the booster, but I never saw it. I say replace the master cylinder and see how it works.

 

If you are concerned, change it. If you have the time, you could pull the booster, dump the contents out, and reinstall it so there is no standing brake fluid. It's your call. No one can make the choice for you. I personally wouldn't change it on my vehicle unless I bought it that way. But I would recommend a customer to have it changed so I wouldn't be liable if/when it did fail.